Interactive Elixir (1.9.1) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> data = [
...(1)>     %{age: 6, name: "Apple"},
...(1)>     %{age: 4, name: "Dog"},
...(1)>     %{age: 1, name: "Cat"},
...(1)>     %{age: 4, name: "Boy"}
...(1)> ]
[
  %{age: 6, name: "Apple"},
  %{age: 4, name: "Dog"},
  %{age: 1, name: "Cat"},
  %{age: 4, name: "Boy"}
]
iex(2)> compare =
...(2)>   fn
...(2)>     x, x -> :eq
...(2)>     x, y when x > y -> :gt
...(2)>     _, _ -> :lt
...(2)>   end
#Function<13.126501267/2 in :erl_eval.expr/5>
iex(3)> age_desc =
...(3)>   fn lhs, rhs ->
...(3)>     case compare.(lhs[:age], rhs[:age]) do
...(3)>       :lt -> false
...(3)>       _ -> true
...(3)>     end
...(3)>   end
#Function<13.126501267/2 in :erl_eval.expr/5>
iex(4)> Enum.sort(data, age_desc)
[
  %{age: 6, name: "Apple"},
  %{age: 4, name: "Dog"},
  %{age: 4, name: "Boy"},
  %{age: 1, name: "Cat"}
]
iex(5)> age_desc_name_asc =
...(5)>   fn lhs, rhs ->
...(5)>     case {compare.(lhs[:age],rhs[:age]), compare.(lhs[:name],rhs[:name])} do
...(5)>       {:lt, _} -> false
...(5)>       {:eq, :gt} -> false
...(5)>       {_,_} -> true
...(5)>     end
...(5)>   end
#Function<13.126501267/2 in :erl_eval.expr/5>
iex(6)> Enum.sort(data, age_desc_name_asc)
[
  %{age: 6, name: "Apple"},
  %{age: 4, name: "Boy"},
  %{age: 4, name: "Dog"},
  %{age: 1, name: "Cat"}
]
iex(7)>